Nine Myanmar police officers were killed in coordinated attacks by insurgents on posts along the border with Bangladesh early on Sunday, an official and police said. No-one has claimed responsibility but a senior local Myanmar official pointed the finger at a militant group from the Muslim Rohingya minority that has been dormant for years. The assaults hit three border posts around 1:30 am near Maungdaw in the impoverished western state of Rakhine, simmering with tensions between Buddhists and Muslim Rohingyas, who are forced to live in dire conditions.

“Altogether nine police were killed, four others were injured and one is still missing,” Tin Maung Swe, a senior official within Rakhine’s state government, told AFP. He added that eight insurgents were also killed in the attacks. Police in the capital Naypyidaw confirmed the attack and said multiple weapons were seized by the assailants. Tin Maung Swe said the attackers were “RSO insurgents”, a reference to a group known as the Rohingya Solidarity Organisation.

He did not elaborate on how he knew this. The RSO was a small Rohingya militant group active in the 1980s and 1990s but has not been heard from in nearly two decades. Rakhine has been effectively split on religious grounds since bouts of communal violence tore through the state in 2012, killing scores and forcing tens of thousands to flee.

The Muslim Rohingya are largely confined to camps and face restrictions which rights groups have likened to apartheid. Several complex ethnic conflicts are rumbling across Myanmar’s borderlands, hampering efforts to build the economy after the end of junta rule.

But compared to the country’s civil war-ravaged eastern and northern border states, Rakhine has not boasted a significant rebel military presence. In the last few years the Arakan Army, a small Buddhist militia which wants an independent homeland in the state, has fought sporadic battles with the military.

Despite their plight the Rohingya do not have a known militant faction fighting for them. In May attackers stormed a security post at a camp for Rohingya refugees in southern Bangladesh, just across the border from Maungdaw.